Semiconductor light-emitting devices may include, for example, light emitting diodes (LEDs) and semiconductor lasers, and may provide high light efficiency. The semiconductor lasers can be classified as two groups: edge emitting lasers, and surface emitting lasers. For edge emitting lasers, the laser light propagates parallel to the wafer surface, while the surface emitting lasers the laser light propagates in the direction perpendicular to the semiconductor wafer surface. The edge emitting lasers are capable of providing high laser output power, simple to fabricate, having high efficiency and compatible with high speed modulation, and thus are used in the fiber optic communication devices for high speed data transmission.
Materials currently used in manufacturing edge emitting laser include Group III-V semiconductors, particularly binary, ternary, and quaternary alloys of group III elements such as gallium, aluminum, and indium, and group V elements such as nitrogen, phosphorus, arsenic, and antimony. The edge emitting laser including III-V semiconductors may be fabricated by epitaxially growing a stack of semiconductor layers of different compositions and dopant concentrations on a substrate. In other words, these semiconductor layers are stacked from the substrate in a direction perpendicular to the substrate. One or more n-type layers may be formed on the substrate and one or more p-type layers may be formed over the one or more n-type layers with one or more layers of an active region formed therebetween. Electrical contacts are formed to connect the n-type and the p-type regions. Laser waveguide is formed using materials with different refractive indexes to confine the light. Light feedback loop is achieved by end mirrors at the end of the cavity or distributed mirrors along the laser waveguide.